If your basement is flooded with more than just a couple of inches (we are talking a foot of water, here), don’t be in too big a hurry to pump it out.
Water in the ground outside your home is pushing hard against the outside of your basement walls. But the water inside your basement is pushing right back.
If you drain your basement too quickly, the pressure outside the walls will be greater than the pressure inside the walls—and that may make the walls and floor crack and collapse, causing serious foundation damage.
To avoid this situation, follow these steps when you pump the water out of your basement:
After floodwaters are no longer on top of the ground, you can start pumping the water out of the basement. Do not use gasoline-powered pumps or generators indoors because gasoline engines create deadly carbon monoxide exhaust fumes. Safety tip: Make sure the electricity to the house is turned off.
Pump the water level down 2 to 3 feet. Mark the level and wait overnight.
Check the water level the next day. If the water went back up, it’s still too early to try to drain the basement. Wait overnight again. Then pump the water down 2 to 3 feet again. Check the level the next day.
When the water stops going back up, pump down another 2 to 3 feet and wait overnight. Repeat steps 4 and 5 until all water is pumped out of the basement.